@mixin border-bottom {
   /* 0.5像素边框 */
    position: relative;
    &::after {
      content: '';
      position: absolute;
      left: 0;
      bottom: 0;
      width: 100%;
      height: 1px;
      /* background: #e9e9e9; */
      background: red;
      transform: scaleY(0.5);
    }
  }
  
  @mixin border($color, $radius) {
    position: relative;
    &::after {
      content: " ";
      transform: scale(0.5);
      position: absolute;
      border: 1px solid $color;
      top: -50%;
      right: -50%;
      bottom: -50%;
      left: -50%;
      border-radius: $radius;
    }
  }
  